1. Field of the Invention
The invention relates in general to an automatic shutoff system for a fluid supply and more particularly to means and methods for (1) detecting fluid movements (2) evaluating detected fluid movements according to predetermined criteria and (3) shutting off the system when undesired flow occurs.
2. Description of the Prior Art
The need for detecting leaks in plumbing systems and responding by closing shutoff valves has been widely appreciated. See for example U.S. Pat. Nos. 4,705,060, 4,518,955, 4,522,229 and 4,180,088. Undetected leaks may cause loss of valuable fluids conducted within the plumbing system, and the leaking fluid may cause extensive damages on the surroundings such as water damage or damage due to corrosion or even explosion.
Automatic shutoff systems heretofore devised experienced difficulty in detecting low volume fluid movement such as might occur due to a very small leak in the system. However, over a period of time, even small leaks may cause extensive damage. Accordingly, it became desirable to provide an effective low flow rate sensor in an automatic fluid shutoff system.
Another problem with prior art fluid shutoff systems arose with regard to providing ample power during normal power outages or failures. If a leak in the plumbing system occurred during an incipient power outage, shutoff systems of the prior art could not respond. Such power failures as well as plumbing system failures can be caused by the same catastrophic occurrence such as an earthquake, tornado, etc. Accordingly, it is necessary under such circumstances that an automatic fluid shutoff system incorporates a low voltage shutoff valve that is fully operable when energized by a low voltage battery. Moreover, it is desirable, if not essential, that a fluid shutoff system be fully operable with minimal power from a battery back up during periods of power outage and also be able to shut down the fluid plumbing system by means of the low voltage shutoff valve if and when the power failure continues past the life of the back up battery.
There are times when the plumbing system of a house or building is monitored and operated such as by a worker or homeowner but also there are times when the plumbing system is not monitored such as when the worker is called away or the home is vacant. If a fluid system malfunction or failure should occur in the absence of a monitoring person, serious damage and flooding could occur. Accordingly it is desirable to provide a highly sensitive means to automatically detect a malfunction and a lower power means to disconnect the fluid supply from the plumbing system. The shutoff should be accomplished within a predetermined time period of uninterrupted water flow when the plumbing system is monitored and within a relatively short time period of uninterrupted water flow when the plumbing system is not monitored by an operator or homeowner.
Accordingly, a general object of the present invention is to provide an automatic shutoff control system for a fluid or plumbing system that solves the aforesaid problems.
Another object of the invention is to provide a highly efficient and sensitive low flow rate sensor by a relatively small amount of power and thus in an automatic fluid shutoff system.
Another object of the invention is to provide a shutoff valve that is fully operable by a low voltage battey in the event of the loss of conventional house power.
Still another object of the invention is to provide an automatic fluid shutoff system that can be adjusted to accomplish system fluid shutoff within a longer period of uninterrupted water flow when the plumbing system is being monitored or to shut off the fluid supply within a relatively shorter predetermined period of uninterrupted water flow when the plumbing system is not being monitored by an operator or a homeowner.
Other objects of the invention are to provide a fluid shutoff system which can be easily installed with a minimum of tools and labor or which is durable and reliable; and one which is particularly well adapted for ease and economy of manufacture.